FIG. 1 illustrates a perspective view of a portion of a prior art earth boring drill bit 8. Here, a cutting element 12 is shown disposed within a pocket of a blade 10. Cutting element 12 is a gage cutter, which is conventionally fabricated as a polycrystalline diamond compact (PDC) cutting element, which cutting element may also be characterized as a polycrystalline diamond cutter (PCD), the structure of which includes a polycrystalline diamond layer 14 on the end face of a carbide body, commonly termed a substrate. As is known, gage cutters are generally disposed along the outermost radial portion, or gage, of the drill bit 8. For dimensional and tolerance purposes, the uppermost cutting surface of the cutting element 12 (as the cutting element 12 is mounted on the drill bit 8, and with respect to the adjacent surface of the drill bit 8) is ground down so the bit diameter is within a specified value to drill a particular size of borehole. The grinding process produces a curved surface, known in the industry as a flat 18. The leading edge of the flat is typically a straight line, and the relatively sharp edge is known to produce high stress concentrations in that area of the PDC layer 14 when formation material is being cut.
A chamfer, indicated by reference numeral 16 in FIG. 1, is typically formed on a portion of the outer edge of the PDC layer 14 of PDC cutting elements. Chamfers generally comprise an angled section, conventionally at a 45° angle to the cutting face of PDC layer 14, on a portion of the front outer radius of the PDC layer. The chamfers are added to the cutting elements to reduce localized stresses on the PDC layer 14 when a cutting element is first cutting formation material. Thus, the inclusion of the chamfer on a cutting element used on the face of a drill bit can help prevent chipping and spalling along this portion of the PDC layer. However, the dimension of the chamfer 16 is small enough so that the forming of the flat 18 when a cutting element 12 is configured as a gage cutter causes the flat to extend radially inwardly on the front portion or cutting face of the PDC layer of the cutting element beyond the inner boundary of the so-called “chamfer envelope” of the PDC layer 14 and thus produces an interface 20 along the boundary where the flat 18 meets with the front portion of the PDC layer 14. The interface 20 has a sharp edge that often experiences high localized stresses during drilling, resulting in development of a damaged portion 21 along this interface 20. Examples of the damaged portion 21 include chips and cracks in the PDC material, and even spallings of masses of PDC material from the PDC layer 14.